The present invention generally relates to an exposure mask and a method of its use for manufacturing a semiconductor device. More specifically, the present invention concerns forming a recess of a bulb-type recess gate which is separated at a given distance from an edge of an active region in a device isolation region.
As a result of the high integration of semiconductor devices, as a line-width of a gate becomes narrower to shorten a channel length, electric characteristics of semiconductor devices are degraded. In order to prevent the degradation, a recess gate has been used. The recess gate increases a gate channel length by etching a semiconductor substrate of a local gate region at a given depth to increase a contact area between an active region and a gate.
However, semiconductor devices become smaller so that the recess and the gate occurs are misaligned. When the misalignment between the recess and the gate occurs, leakage current is generated. As a result, the line-width of the recess where the recess contacts with the gate is formed to be narrow in consideration of arrangement margin. In order to secure the effective area, the lower portion of the recess is formed to have a bulb-type.